In normal production of mechanical products and mechanical units incorporating printed circuit boards (PCBs) that mounts electronic parts thereon, a mechanical CAD (Computer Aided Design) system and a PCB CAD system are used. Mechanical design by a mechanical CAD system is carried out in parallel to electric design by a PCB CAD system.
Here, a mechanical CAD system designs mechanical products and mechanical units that are to accommodate PCBs, and for this purpose, creates part data about casing, electronic parts, and mechanical parts serving as parts to be designed.
A PCB CAD system makes an electric design of the outer shapes of PCBs that is the boards to be designed and wiring patterns on the PCBs, and thereby creates board data. Here, a wiring pattern includes footprints that attach terminals of an electronic part disposed thereon through soldering or through-holes that fix terminals of an electronic device after the terminals are inserted into the holes.
As the above, the mechanical design by a mechanical CAD system and the electric design by a PCB CAD system are carried out in parallel to each other, so that the part data and the board data are created by different systems of the mechanical CAD system and the PCB CAD system, respectively. For this reason, there is a requirement of confirming the interference or other relationship between the part data and the board data. Accordingly, the confirmation requires the mechanical CAD system and the PCB CAD system to unite with each other so that both the part data and the board data are referred and compared with each other.
As one example, the following manners (a) and (b) each conventionally unite a mechanical CAD system and a PCB CAD system 2, that is, unite part data and board data.
(a) The designer captures, through manual operation, board data created by a PCB CAD system into a mechanical CAD system, and, on the mechanical CAD system, confirms the arrangement position of parts and checks interferences and spaces between each part to be mounted onto a PCB and a structure created by the mechanical CAD. Specifically, the designer determines the positional relationship among a casing, parts, and a PCB through manual operation. At that time, the designer determines the positional relationship in the mechanical CAD system using the predetermined reference position (reference origin) for each part on the PCB and the reference position of each part. Thereby, both the part data created by the mechanical CAD system and the board data created by the PCB CAD system can be confirmed.
(b) There is proposed a technique of, when the board data created by the PCB CAD system is captured into the mechanical CAD system, replacing the respective parts of the PCB CAD system with detailed part data created by the mechanical CAD system using part data of the PCB CAD system.
[Patent Reference 1] Japanese Laid-Open Patent Publication No. 2008-84211
[Patent Reference 2] Japanese Laid-Open Patent Publication No. 2009-116743
[Patent Reference 3] Japanese Laid-Open Patent Publication No. HEI 9-167172
[Patent Reference 4] Japanese Laid-Open Patent Publication No. HEI 9-311878
[Patent Reference 5] Japanese Laid-Open Patent Publication No. 2002-324084
However, since the above manner (a) compels the designer to capture data and determine the positional relationship through manual operation, which means a large amount of load of the designer. If the data created by an external CAD system does not have a reference origin, the designer determines the positional relationship through visually checking the arrangement position of each electronic part with respect to footprints or through-holes on a monitor. This operation has possibilities of human judging mistake, increasing manpower, complexity of confirmation, and increasing steps of the confirmation.
A part model created by the mechanical CAD system is created in the different manner from that of a board model created by the PCB CAD system and has an origin different from that of the board model. Therefore, replacement (see the above manner (b)) of the part data on the board model created by the PCB CAD system with a part model created by the mechanical CAD system on the basis of the board model cannot obtain the right arrangement position of the part. Accordingly, the designer has to correct the position of the model through manual operation, leading to increasing manpower, complexity of confirmation, and increasing steps of the confirmation.